(1) Field of the Invention
The present invention relates to a camera-mounting device that is used for attaching, for example, a monitor camera or the like to a ceiling above a front glass of a mobile body such as a car in a suspended state.
(2) Description of the Related Art
In a conventional camera-mounting device, securing and releasing mechanisms (mainly, screws) are placed near a rotation ball shaft so as to firmly secure a camera mounted on a—(for example, see Japanese Unexamined Patent Publication 10-288811). FIGS. 9 and 10 show a conventional camera-mounting device described in the Patent Publication.
FIG. 9 is an exploded perspective view showing one portion of a case main body, and FIG. 10 is a longitudinal cross-sectional view. This camera-mounting device has a structure in which a mount base 121 having a truncated cone shape with a cone face 122 being formed on its upper portion is installed on the bottom of a cylindrical case main body 101, and a belt-shaped tightening mechanism 131 having a handle 141 is placed on the upper portion of this mount base 121. Moreover, a ball shaft 111 having a spherical shape is mounted on the upper portion of the tightening mechanism 131. Cone faces 132 and 133 are formed on the upper and lower inner faces of the ring portion of the tightening mechanism 131, and the cone face 133 on the lower side and the cone face 122 of the mount base 121 are made in contact with each other, with the ball shaft 111 having a spherical shape being mounted on the cone face 132 on the upper side. Here, the upper portion of the ball shaft 111 is made in contact with the inner face of the upper portion of the case main body 101.
In the above-mentioned structure, when the handle 141 is rotated in a securing direction, the tightening mechanism 131 is tightened inward by functions of the handle 141 and the screw shaft 142 so that the ring portion of the tightening mechanism 131 is allowed to intrude between the ball shaft 111 and the mount base 121. Since the ball shaft 111, the tightening mechanism 131 and the mount base 121 are placed in the case main body 101 without any gap, the ball shaft 111 is raised by tilt vectors exerted on the cone faces 132 and 133 formed on the upper and lower ends of the tightening mechanism, the cone face 122 of the mount base 121 and the ball shaft 111, so as to be firmly pressed onto the inner face of the upper portion of the case main body 101 so that the ball shaft 111 is secured onto the case main body 101.
In the above-mentioned conventional structure, however, in the case of poor machining precision of parts, the ball shaft 111 fails to obtain a sufficient holding strength to the case main body 101. For this reason, a special machining process is required for manufacturing the tilt face to cause the parts to become expensive. Moreover, since the securing and releasing operations for the ball shaft 111 are carried out by the screw shaft 142 of the handle 141, the screw tends to become loose due to vibration when installed in a mobile body such as a vehicle, resulting in a problem of degradation in the securing force.
In order to solve these problems, the objective of the present invention is to provide a camera-mounting device that exerts a firm securing force, and is resistive to vibration.